feat(expect): fixes to contain with strings

src/Expectation.php

@@ -147,7 +147,7 @@ final class Expectation
      */
     public function toContain($value): Expectation
     {
-        if (is_string($value)) {
+        if (is_string($this->value)) {
             Assert::assertStringContainsString($value, $this->value);
         } else {
             Assert::assertContains($value, $this->value);

tests/.snapshots/success.txt

@@ -119,7 +119,8 @@
   ✓ not failures
 
    PASS  Tests\Expect\toContain
-  ✓ passes
+  ✓ passes strings
+  ✓ passes arrays
   ✓ failures
   ✓ not failures
 
@@ -308,5 +309,5 @@
    WARN  Tests\Visual\Success
   - visual snapshot of test suite on success
 
-  Tests:  6 skipped, 181 passed
-  Time:   5.70s
+  Tests:  6 skipped, 182 passed
+  Time:   5.72s

tests/Expect/toContain.php

@@ -2,10 +2,14 @@
 
 use PHPUnit\Framework\ExpectationFailedException;
 
-test('passes', function () {
+test('passes strings', function () {
     expect([1, 2, 42])->toContain(42);
 });
 
+test('passes arrays', function () {
+    expect('Nuno')->toContain('Nu');
+});
+
 test('failures', function () {
     expect([1, 2, 42])->toContain(3);
 })->throws(ExpectationFailedException::class);